Diaphragm structure for a multi-stage centrifugal gas compressor

ABSTRACT

The diaphragm structure for multi-stage centrifugal compressors consists of two pieces cast separately. One piece is fixed at its periphery in the compressor casing in the conventional manner. The second piece is spaced in a direction axially of the compressor from the first piece to form in conjunction therewith a gas inlet passage terminating at the intake of the impeller. The second piece is spaced from the first piece by a plurality of radially disposed vanes formed integral with the second piece. The side surface of the first piece confronting the second piece is formed with a recess. Said vanes are formed at their free edges with a circular rib disposed in the recess. The rib and recess are formed with integral interlocking means.

United States Patent 1191 Benjamin July 23, 1974 DIAPHRAGM STRUCTURE FOR A MULTl-STAGE CENTRIFUGAL GAS Primary Examiner-Henry F. Raduazo O E R Attorney, Agent, or Firm-J. Raymond Curtin [75] Inventor: Herschel A. Benjamin, Greensburg,

Pa. [57] ABSTRACT [73] Assignee: Carrier Corporation, Syracuse, NY. The diaphl'agm stfucture for multi'stage centrifugal compressors consists of two pieces cast separately. [22] Filed: 1973 One piece is fixed at its periphery in the compressor [211 App} 336,847 casing in the conventional manner. The second piece is spaced in a direction axially of the compressor from the first piece to form in conjunction therewith a gas C 415/199 A, 4l5/DlG. 5, 415/219 C inlet passage terminating at the intake of the impeller. Cl. The second piece is spaced from the first piece a [58] Field of Search-m 415/199 219 C, 5 plurality of radially disposed vanes formed integral with the second piece. The side surface of the first [56] References cued piece confronting the second piece is formed with a UNITED STATES PATENTS recess. Said vanes are formed at their free edges with 979,634 12/1910 Aki ff n 415/199 A a circular rib disposed in the recess. The rib and re- FOREIGN PATENTS OR APPLICATIONS cess are formed wlth mtegral mterlockmg means. 450,053 1/1913 France 415/199 A 3 Claims, 3 Drawing Figures W -ef H 4 DIAPHRAGM STRUCTURE FOR A MULTI-STAGE CENTRIFUGAL GAS COMPRESSOR BACKGROUND OF THE INVENTION Conventionally, diaphragms and multi-stage centrifugal gas compressors are produced in the form of an integral one-piece casting. The patterns and core boxes for such an intricate, large casting are extremely expensive. Also, it is difficult to machine the large castings and they cannot be modified to any appreciable extent for different compressor operations.

This invention has as an object a diaphragm construction embodying two separate castings, patterns for which are much cheaper to construct. The smaller patterns are more readily handled in the foundry, reducing casting cost. The smaller castings are also more readily machined and may be machined for use in different compressor operations.

SUMMARY OF THE INVENTION The diaphragm structure consists of a first pair of castings semiannular in general form. These castings are attached at their peripheries to the compressor housing and encircle the impeller of a stage. A second pair of castings are spaced axially from the first pair and form in conjunction therewith a gas flow passage terminating at the entrance of the impeller. The second pair of castings are provided on their sides confronting the first pair with a series of radially disposed integral vanes extending across the inlet passage. The free edges of the vanes are formed with a circular rib and the side surface of the first pair of castings confronting the vanes are formed with a circular recess for the reception of the ribs. The ribs and the recesses are formed with interlocking means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view taken on a line corresponding to line ll, FIG. 2;

FIG. 2 is a view taken on line 22, FIG. I; and

FIG. 3 is a view taken on line 33, FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT A diaphragm structure consists of a pair of castings of semiannular form. These castings are formed at their peripheries with ribs 13 positioned in circumferentially extending grooves formed on the inner surface of the compressor housing 15. The castings 10 are arranged to encircle the impeller 16. The side surface 17 of the castings 10 form one side of the diffuser passage extending radially from the periphery of the impeller.

The second pair of castings II are formed with a plurality of integral radially disposed vanes 23 extending across the passage between the castings 10, 11, the passage terminating at its inner end in communication with the inlet of the impeller 16.

The free edges of the vanes 23 terminate in close proximity to the sides of the castings l7 confronting the castings 11. These free edges are formed with an integral circular rib 25 and the confronting side surface of the castings I0 is formed with a circular recess for the reception of the ribs. The inner side surfaces of the recesses formed in the side surface 27 of the castings 10 are formed with a recess for the reception of a flange 28 formed on the ribs 25. With this arrangement, the ribs are interlocked with the castings l0 and form the supporting structure for the castings 11.

The inner surface edge of the castings 10 is machined for interlocking engagement with a labyrinth seal structure 33, serving to prevent gas leakage along the shroud of the impeller 16. In like manner, the inner edges of the castings 11 are machined for the reception of labyrinth seals 35 to prevent gas leakage along the shaft 37.

While I have described the preferred embodiments of my invention, it is to be understood that the invention is not limited thereto but may be otherwise embodied within the scope of the following claims.

I claim:

1. A diaphragm structure for a multi-stage centrifugal gas compressor having a horizontal split casing including a first pair of semicircular annular body members mounted at their periphery in the compressor casing, said first body members encircling an impeller stage of the compressor and having a side surface extending radially from the periphery of the impeller forming one side wall of a diffuser passage extending from the impeller, the diaphragm structure also including a second pair of semiannular members spaced axially from said first members and forming in conjunction with the opposite side surface thereof a gas inlet passage terminating at the intake of the impeller, the side surfaces of each of said second members confronting said first members and being formed with a plurality of radially disposed circumferentially spaced apart integral vanes extending transversely across the inlet passage with the free side edges of the vanes positioned in close proximity to the first body members, the improvement comprising:

a semicircular support rib connected to the free side edge of each of said vanes being coextensive with and arranged to mate with a complimentary groove formed in said first pair of semiannular members to support the second members in cantilever suspension from said first members whereby said diaphragm structure is suspended from the compressor casing; and

locking means operatively associated with said support rib for aligning said second members in relation to said first members.

2. The diaphragm structure of claim 1 whereby said locking means comprises a radially extended key arranged for seating within the complimentary groove fonned in said first member whereby said second member is prevented from shifting in relation to said first member.

3. The apparatus of claim 2 wherein said second members are arranged to support a seal which encompasses the shaft of said compressor. 

1. A diaphragm structure for a multi-stage centrifugal gas compressor having a horizontal split casing including a first pair of semicircular annular body members mounted at their periphery in the compressor casing, said first body members encircling an impeller stage of the compressor and having a side surface extending radially from the periphery of the impeller forming one side wall of a diffuser passage extending from the impeller, the diaphragm structure also including a second pair of semiannular members spaced axially from said first members and forming in conjunction with the opposite side surface thereof a gas inlet passage terminating at the intake of the impeller, the side surfaces of each of said second members confronting said first members and being formed with a plurality of radially disposed circumferentially spaced apart integral vanes extending transversely across the inlet passage with the free side edges of the vanes positioned in close proximity to the first body members, the improvement comprising: a semicircular support rib connected to the free side edge of each of said vanes being coextensive with and arranged to mate with a complimentary groove formed in said first pair of semiannular members to support the second members in cantilever suspension from said first members whereby said diaphragm structure is suspended from the compressor casing; and locking means operatively associated with said support rib for aligning said second members in relation to said first members.
 2. The diaphragm structure of claim 1 whereby said locking means comprises a radially extended key arranged for seating within the complimentary groove formed in said first member whereby said second member is prevented from shifting in relation to said first member.
 3. The apparatus of claim 2 wherein said second members are arranged to support a seal which encompasses the shaft of said compressor. 